Belt retractor

ABSTRACT

A belt retractor for a vehicle safety belt with a frame has a belt reel ( 10 ) rotatably mounted in the frame, a coupling disk ( 14 ) rotatably mounted relative to the belt reel ( 10 ), and a clip spring ( 16 ) which is attached to the belt reel ( 10 ) and to the coupling disk ( 14 ).

TECHNICAL FIELD

The invention relates to a belt retractor for a vehicle safety belt.

BACKGROUND OF THE INVENTION

The belt retractor serves to make the vehicle safety belt available to avehicle occupant. In the normal operating state the vehicle safety beltmay be unwound from a belt reel or wound up again on the same. There isprovided a locking mechanism which is capable of blocking the belt reelin a manner sensitive to the belt webbing or in a vehicle-sensitivemanner, hence dependent on parameters such as the belt webbing orvehicle acceleration. For the vehicle or belt webbing sensitive blockingof the belt reel modern belt retractors have a coupling disk whichrotates along with the belt reel in the normal operating state. For thevehicle-sensitive activation of the locking mechanism the coupling diskis provided with a toothing, a locking element of a vehicle-sensitivesensor being able to engage in the toothing. An inertial element isconnected to the coupling disk for the belt webbing-sensitive activationof the locking mechanism. If the coupling disk remains behind therotation of the belt reel on account of the mass inertia, it causes alocking pawl to pivot into a locking toothing of the frame by means ofan actuating element.

DE 102 13 248 A1 shows a coupling disk whose basic position with respectto the belt reel is determined by a spiral spring. The production ofsuch spiral springs is complicated and therefore expensive.

It is the object of the invention to provide a belt retractor that canreadily and cost-effectively be manufactured.

BRIEF SUMMARY OF THE INVENTION

According to the invention, a belt retractor for a vehicle safety beltwith a frame has a belt reel rotatably mounted in the frame, a couplingdisk rotatably mounted relative to the belt reel, and a clip springwhich is attached to the belt reel and to the coupling disk.

According to the invention there is used a clip spring which determinesthe basic position of the coupling disk with respect to the belt reel.The clip spring is distinguished by a plurality of advantages. Theproduction of clip springs is simple, since among other things thespring force of the clip springs is solely adjusted by their tensioning,whilst in the case of spiral springs the spring force depends on thenumber of the spirals, the diameter thereof, etc. The material usagewith clip springs is small, which is why clip springs are low-priced.Besides, the transport of clip springs is simple, since they cannotinterlock. Therefore, no blister packages are required. When clipsprings are used in belt retractors, the moment when the locking pawl iscaused to engage is determined by the torque caused by the clip springand the contact friction of the coupling disk on the reel axle. In thebelt retractor in, accordance with the invention this frictional forceis adjustable more variably than in the prior art. Depending on theforceless geometry of the clip spring (production state) a torque and aforce between the coupling disk and the reel axle may be applied by thesystematic tensioning in the state of installation. In the beltretractor in accordance with the invention the contact point of the clipspring to the coupling disk lies opposite the contact point of thelocking pawl and is mounted rotatably. The radial component of thetensioning force may, for example, be used to change the amount and thedirection of the frictional force caused by the weight of the lockingpawl such that the frictional force depends less on the position of thelocking pawl. A frictional force whose amount is more constant than inthe prior art therefore results in a more defined breakaway in allpositions of the locking pawl. Besides, in spiral springs used in theprior art disturbing noises occurred on account of the spirals strikingagainst one another, which is known as “spring whizzing” and which isabsent in clip springs. Furthermore, clip springs may be simulated moreeasily. It is, moreover, advantageous that clip springs have a higherresistance to the action of a tensioner, since they do not becomeentangled in a higher acceleration.

Preferably, the clip spring is configured symmetrically and thereforedoes not have to be oriented relative to the reel axle prior to theinstallation, i.e., it does not have to be rotated. Therefore, theinstallation is simple.

Preferably, the belt reel includes a reel axle, and the coupling disk ismounted on the reel axle, the clip spring being attached to the beltreel and to the coupling disk such that it does not engage the reelaxle. Since the clip spring does not engage the reel axle, the latter isnot stressed, and disturbing noises are avoided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exploded view of a part of a belt retractor inaccordance with the invention,

FIG. 2 shows a perspective side view of a part of the belt retractor ofFIG. 1, and

FIG. 3 shows a side view of a part of the belt retractor of FIG. 1.

FIGS. 1 to 3 show a part of a belt retractor including a belt reel 10.The belt reel 10 is rotatably mounted about a reel axle 12 in a frame(not shown).

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENT

There is provided a coupling disk 14 which is coaxially connected to thebelt reel 10. The basic position of the coupling disk 14 with respect tothe belt reel 10 is determined by a clip spring 16, the first end of theclip spring 16 being attached to the coupling disk 14 and its second endbeing attached to the belt reel 10 (FIGS. 2 and 3), in particular, insuch a manner that the clip spring 16 does not engage the reel axle 12and such that it is tensioned. The clip spring 16 is directly attachedto the coupling disc 14. For the attachment to the coupling disk 14 andto the belt reel 10, the ends of the clip spring 16 are bent in theshape of hooks (the hooks 17). The clip spring 16 is eccentricallyattached to the belt reel 10 and to the coupling disk 14 (with respectto the reel axle 12) and rotatably supported on the coupling disk 14.

On its outer periphery the coupling disk 14 is provided with a toothing18 which may cooperate with a vehicle-sensitive sensor element (notshown).

The coupling disk 14 is integrally connected to an inertial element (notshown). Along with the inertial element the coupling disk 14 forms thesensor element that is sensitive to the belt webbing and that will bedescribed in more detail hereinafter.

An actuating element 22 (FIGS. 2 and 3) is connected to the couplingdisk 14 via a connecting arm. The actuating element 22 engages a lockingpawl 20, in particular into a control contour 24 which is situatedwithin the locking pawl 20. The locking pawl 20, which is disposed in arecessed pocket of the belt reel 10, is configured such that it may becaused to engage in a locking toothing (not shown) which is provided onthe frame. In so doing, the bearing point of the locking pawl 20substantially lies opposite (with regard to the axis of rotation of thebelt reel 10 and the coupling disk 14) the bearing point of the clipspring 16 on the coupling disk 14.

Along with the inertial element the coupling disk 14 forms the sensorelement that is sensitive to the belt webbing. In a sudden rotation ofthe belt reel 10 the coupling disk 14 stops or trails behind therotation of the belt reel 10. On account of the relative rotationbetween the belt reel 10 and the coupling disk 14 the actuating element22, which is connected to the coupling disk 14 via the connecting arm,shifts such that because of the engagement in the control contour 24 ofthe locking pawl 20 it pivots the locking pawl 20 in such a manner thatthe same is caused to engage in the locking toothing of the frame.

The radial component of the tensioning force of the clip spring 16 isused to change the amount and the direction of the frictional forcecaused by the weight of the locking pawl 20 such that the same dependsless on the position of the locking pawl 20. A frictional force whoseamount is more constant than in the prior art therefore results in amore defined breakaway in all positions of the locking pawl 20.

1. A belt retractor for a vehicle safety belt with a frame, said beltretractor including a belt reel (10) rotatably mounted in said frame, acoupling disk (14) rotatably mounted relative to said belt reel (10),and a clip spring (16) which is attached to said belt reel (10) and tosaid coupling disk (14).
 2. The belt retractor according to claim 1,wherein said clip spring (16) is configured symmetrically.
 3. The beltretractor according to claim 1, wherein said belt reel (10) includes areel axle (12), and said coupling disk (14) is mounted on said reel axle(12), said clip spring (16) being attached to said belt reel (10) and tosaid coupling disk (14) such that it does not engage said reel axle(12).
 4. The belt retractor according to claim 1, wherein said clipspring (16) is eccentrically attached to at least one of said belt reel(10) and said coupling disk (14).
 5. The belt retractor according toclaim 1, wherein said coupling disk (14) includes an actuating element(22), and in that a locking pawl (20) is provided, said actuatingelement (22) being adapted to engage said locking pawl (20).